Quantum Physics
We characterize quantum motion based on the susceptibility of a quantum state to weak local state conversion. The inverse susceptibility can be interpreted as a passage speed characterizing local motion independently of probability…
Jacobi diagonalization is a long-established numerical algorithm for the spectral decomposition of Hermitian and, more generally, normal matrices. In this work, we develop a qudit-native quantum realization of the Jacobi diagonalization…
In [Phy. Rev. Lett., 98, 260501 (2007)] and previous papers, the W-like states were used in many quantum communication schemes, distillation, teleportation and superdense coding. So far, no one has compared the W-like states with the W…
We report a fibre-integrated heralded single-photon source based on a commercial Zn-indiffused MgO:PPLN ridge waveguide operated in Type-0 degenerate spontaneous parametric down-conversion (SPDC). The device emits a broadband spectrum…
Response-register quantum oracles admit two complementary operational interpretations: value readout and phase kickback. Although their computational equivalence is well understood, the quantitative relation between these two operational…
Matrix chain multiplication -- computing $\mathcal{W} = M^{(0)}\cdots M^{(K-1)}$ where $M^{(k)} \in \mathbb{R}^{P_k \times P_{k+1}}$ -- arises in scientific computing, machine learning, and graph analysis. Despite the importance of this…
Entangling gates of trapped ions are typically mediated by collective motional degrees of freedom. Weak coupling between qubit and motional degrees of freedom and the resulting harmonic dynamics give access to a broad range of gate schemes,…
Fully-connected transverse interactions have been considered as catalysts for quantum annealing that could mitigate exponentially small gaps and circumvent first-order phase transitions, but their experimental implementation remains…
The physical content of a theory is not intrinsically tied to any single mathematical formalism. Both classical and quantum mechanics admit equivalent representations, notably in phase space and in Hilbert space, related by the Wigner-Weyl…
We study entanglement harvesting with particle detectors coupled to the renormalized energy density of a massless scalar field. Our analysis identifies the distributional mechanism underlying the persistent ultraviolet divergences…
Dissipative cat qubits exponentially suppress one Pauli error channel with the mean photon number, leaving the conjugate bit-flip error as the dominant failure mode. This strong noise bias makes the full machinery of general quantum error…
General relativity (GR) is naturally organized around spacetime events and their causal order, whereas quantum field theory (QFT) is formulated in terms of states, operators, and unitary evolution, without an intrinsic criterion for when a…
Efficient communication between distant qubits is one of the central challenges in scaling quantum processors. Although engineered spin chain protocols have been extensively investigated theoretically, their experimental realization has…
Parameterized quantum circuits~(PQCs) constitute a central building block of variational quantum algorithms~(VQAs) and quantum machine learning~(QML) methods. Existing ansatz designs often adopt hardware-agnostic or simplified 1D chain/ring…
A Lorentz boost acts on the canonical spin of a massive particle through a momentum-dependent Wigner rotation. We show that, for one fixed observer boost, reducing over an uncertain momentum can strictly contract every pairwise spin-state…
Credit Valuation Adjustment (CVA) requires repeated risk-neutral expectation estimation, making it a natural test bed for quantum amplitude estimation, whose coherent amplification can in principle reduce Monte Carlo sampling cost. Whether…
Unlike in finite dimensions, quantum information in continuous-variable systems has the peculiar feature that without imposing physical constraints, the sample complexity of state tomography can be unbounded. Remarkably, this is even the…
A central model in quantum machine learning is the quantum neural network (QNN), whose design requires balancing expressivity and trainability. Technically, expressivity is studied through circuit-function analysis, such as quantum signal…
A finite quantum reference token with group-valued misalignment induces a random-unitary channel, but optimal degradation is generally an optimization over all quantum post-processings. For a unitary representation U of a finite group G, we…
We demonstrate a nonreciprocal quantum Mpemba effect. Consider a broad class of open quantum systems, each coupled to two isomorphic reservoirs through symmetric ports. Interchanging the parameters of the two reservoirs -- a discrete…